Add Flowtype (WIP)

[AlexKVal]

I will be gradually adding commits step by step to facilitate review and for earlier feedbacks.

I've started to learn flow. Yay _o_/ 😄

But IMHO
Adding flowtype annotations to the library is kinda Pandora's box.
It adds a lot of additional maintenance burden.

The first three commits:
green https://travis-ci.org/AlexKVal/react_on_rails/builds/153954865

src/Authenticity.js
without {content?: string} it warns about

property `content` Property not found in HTMLElement

because it is a dynamic property from document.querySelector('meta[name="csrf-token"]')

The line
lib/generators/react_on_rails/templates/node/base/client/node/server.js has been added to .eslintignore because of #469 merging with linting errors 😈
I'll remove it after the master branch will have resolved linting issues.

Notes about 'fsevents' bug

After a fresh npm i installation of all packages with node@6 version
running of npm run build or build-watch
throws this node's error:

v8::ObjectTemplate::Set() with non-primitive values is deprecated

babel-cli uses chokidar which uses not the latest fsevents
npm i fsevents@latest command solves the problem.
The cause of it fsevents/fsevents#128
Probably we should add the latest fsevents version to package.json
via npm i -D fsevents@latest command.

Notes about Atom's linter-flow

I've managed to get it working only with node@6.3.1 version (out of 6th versions)
linter-flow doesn't work with the latest (at the moment) node@6.4.0. (w/o errors. it just doesn't show any warnings in Atom)

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This change is

[coveralls]

Changes Unknown when pulling 9af0cd8 on AlexKVal:flow into * on shakacode:master*.

[alexeuler]

Review status: 0 of 7 files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

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node_package/src/context.js, line 5 [r1] (raw file):

 * @returns {boolean|Window|*|context}
 * @flow
 */

I think it might be better to put // @flow as a separate line at the top, o/w it's lost in the comment description.

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Comments from Reviewable

[justin808]

@AlexKVal Did we not need to add the params for flow?

We should probably have this in the eslintrc, but only for the library, not the samples...

  flowtype/require-parameter-type: 2
  flowtype/require-return-type:
    - 2
    - always
    -
      excludeArrowFunctions: expressionsOnly
  flowtype/space-after-type-colon:
    - 2
    - always
  flowtype/space-before-type-colon:
    - 2
    - never
  flowtype/require-valid-file-annotation:
    - 2
    - always
  flowtype/valid-syntax: 2

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Review status: 0 of 7 files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

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node_package/src/context.js, line 5 [r1] (raw file):

Previously, alleycat-at-git (Alexey) wrote…

I think it might be better to put // @flow as a separate line at the top, o/w it's lost in the comment description.

I agree with

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Comments from Reviewable

[justin808]

Reviewed 7 of 7 files at r1.
Review status: all files reviewed at latest revision, 2 unresolved discussions, some commit checks failed.

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node_package/src/Authenticity.js, line 10 [r1] (raw file):

  },

  authenticityHeaders(otherHeaders: Object = {}) {

This needs to be string values in the object.

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Comments from Reviewable

[AlexKVal]

@alleycat-at-git thank you for the help. I wasn't sure what is the best way.

@justin808 thank you for the rules for 'eslint'. I'll implement them one by one.

[coveralls]

Coverage remained the same at 82.609% when pulling 7cac593 on AlexKVal:flow into 5bae865 on shakacode:master.

[coveralls]

Coverage remained the same at 82.609% when pulling a07244e on AlexKVal:flow into 5bae865 on shakacode:master.

[coveralls]

Coverage remained the same at 82.609% when pulling a07244e on AlexKVal:flow into 5bae865 on shakacode:master.

[justin808]

Nice work. A couple ideas.

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Reviewed 4 of 5 files at r2, 1 of 1 files at r3.
Review status: all files reviewed at latest revision, 4 unresolved discussions.

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node_package/src/Authenticity.js, line 10 [r3] (raw file):

  },

  authenticityHeaders(otherHeaders: {[id:string]: string} = {}) {

It seems a bit odd for object properties to be a string.

However, this is from the example (kval), so maybe we use key

type MapOfNumbers = { [key: string]: number };
var numbers: MapOfNumbers = {
  ten: 10,
  twenty: 20,
};

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node_package/src/generatorFunction.js, line 12 [r3] (raw file):

 * @returns {boolean}
 */
export default function generatorFunction(component: any) {

https://flowtype.org/docs/union-intersection-types.html#_

This one is either

React.createClass (probably an object)
ES6 Class
Function

Then again, any might be good enough.

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Comments from Reviewable

[AlexKVal]

Review status: all files reviewed at latest revision, 4 unresolved discussions.

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node_package/src/Authenticity.js, line 10 [r3] (raw file):

Previously, justin808 (Justin Gordon) wrote…

It seems a bit odd for object properties to be a string.

However, this is from the example (kval), so maybe we use key

type MapOfNumbers = { [key: string]: number };
var numbers: MapOfNumbers = {
  ten: 10,
  twenty: 20,
};

Yes I just got it from `flowtype.org/examples` as is.

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node_package/src/generatorFunction.js, line 12 [r3] (raw file):

Previously, justin808 (Justin Gordon) wrote…

https://flowtype.org/docs/union-intersection-types.html#_

This one is either

React.createClass (probably an object)
ES6 Class
Function

Then again, any might be good enough.

I have no idea (yet) how to describe such complex types in `flowtype`. My goal is to satisfy all warnings the simplest possible way and only then start to re-write it with more elaborate and complex flowtype's descriptors.

I'm implementing flowtype first time ever. I have no experience with it at all.
So I really appreciate all the help! Thank you. 🍒

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Comments from Reviewable